Personalized voltage maps guided by cardiac magnetic resonance in the era of high-density mapping

BACKGROUND

Voltage mapping could identify the conducting channels potentially responsible for ventricular tachycardia (VT). Standard thresholds (0.5-1.5 mV) were established using bipolar catheters. No thresholds have been analyzed with high density mapping catheters. In addition, channels identified by cardiac magnetic resonance (CMR) has been proven to be related with VT.

OBJECTIVES

To analyze the diagnostic yield of a personalized voltage map using CMR to guide voltage thresholds adjustment.

METHODS

All consecutive patients with scar-related VT undergoing ablation after CMR (October 2018-December 2020) were included. First, personalized CMR-guided voltage thresholds were defined systematically according to scar and channels distribution. Second, to validate these new thresholds, a comparison with standard thresholds (0.5-1.5mV) was carried out. Tissue characteristics of areas identified as deceleration zones (DZ) were recorded for each pair of thresholds. In addition, the relation of VT circuits with voltage channels was also analyzed for both maps.

RESULTS

32 patients were included (age 66.6±11.2 years; 78.1% ischemic cardiomyopathy). Overall, 52 DZs were observed:44.2% were identified as border zone tissue with standard cutoffs vs. 75.0% using personalized voltage thresholds (p=0.003). Of 31 VT isthmuses detected, only 35.5% correlated with a voltage channel with standard thresholds vs. 74.2% using adjusted thresholds (p=0.005). Adjusted cutoff bipolar voltages that better matched CMR were 0.51±0.32 and 1.79±0.71mV with very high interindividual variability (from 0.14-1.68mV to 0.7-3.21mV).

CONCLUSION

Personalized voltage CMR-guided maps enable a clear better identification of the substrate with a higher correlation with both DZs and VT isthmuses than conventional voltage maps using fixed thresholds.

Regional conduction velocities determined by non-invasive mapping are associated with arrhythmia-free survival after atrial fibrillation ablation

BACKGROUND

Atrial arrhythmogenic substrate is a key determinant of atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI), and reduced conduction-velocities have been linked to adverse outcome. However, a non-invasive method to assess such electrophysiological substrate is not available to date.

OBJECTIVE

This study aimed to non-invasively assess regional conduction-velocities and their association with arrhythmia-free survival following PVI.

METHODS

52 consecutive patients scheduled for AF ablation (PVI-only) and 19 healthy controls were prospectively included and received electrocardiographic imaging (ECGi) to non-invasively determine regional atrial conduction-velocities in sinus rhythm. A novel ECGi technology obviating the need of additional CT- or CMR-imaging was applied and validated using invasive mapping.

RESULTS

Mean ECGi-determined atrial conduction-velocities were significantly lower in AF-patients than in healthy controls (1.45±0.15 versus 1.64±0.15m/s; p<0.0001). Differences were particularly pronounced in a regional analysis considering only the segment with the lowest average conduction-velocity in each patient (0.8±0.22 versus 1.08±0.26m/s; p<0.0001). This average conduction velocity of the "slowest" segment was independently associated with arrhythmia recurrence and better discriminated between PVI-responders and non-responders than previously proposed predictors including left atrial size or late-gadolinium-enhancement (MRI). Patients without slow-conduction areas (mean conduction-velocity <0.78m/s) showed significantly higher 12-months arrhythmia-free survival than those with one or more slow-conduction areas (88.9% versus 48.0%, p=0.002).

CONCLUSIONS

This is the first study to investigate regional atrial conduction velocities non-invasively. The absence of ECGi-determined slow-conduction areas well discriminates PVI-responders from non-responders. Such non-invasive assessment of electrical arrhythmogenic substrate may guide treatment strategies and be a step towards personalised AF therapy.

Same-day discharge after atrial fibrillation ablation under a nurse-coordinated standardized protocol

AIMS

Same-day discharge (SDD) after atrial fibrillation (AF) ablation is an effective means to spare healthcare resources. However, safety remains a concern, and besides structural adaptations, SDD requires more efficient logistics and coordination. Therefore, in this study, we implement a streamlined, nurse-coordinated SDD programme following a standardized protocol.

METHODS AND RESULTS

As a dedicated SDD coordinator, a nurse specialized in ambulatory cardiac interventions was in charge of the full SDD protocol, including eligibility, patient flow, in-hospital logistics, patient education, and discharge as well as early post-discharge follow-up by smartphone-based virtual visits. Patients planned for AF ablation were considered eligible if they had a left ventricular ejection fraction (LVEF) ≥35%, with basic support at home and accessibility of the hospital within 60 min also forming a part of the eligibility criteria. A total of 420 consecutive patients were screened by the SDD coordinator, of whom 331 were eligible for SDD. The reasons for exclusion were living remotely (29, 6.9%), lack of support at home (19, 4.5%), or LVEF <35% (17, 4.0%). Of the eligible patients, 300 (91%) were successfully discharged the same day. There were no major post-SDD complications. Rates of unplanned medical attention (19, 6.3%) and 30-day readmission (5, 1.6%) were extremely low and driven by femoral access-site complications. These were significantly reduced upon the introduction of compulsory ultrasound-guided punctures after the initial 150 SDD patients (P = 0.0145). Standardized SDD coordination resulted in efficient workflows and reduced the total workload of the medical staff.

CONCLUSION

Same-day discharge after AF ablation following a nurse-coordinated standardized protocol is safe and efficient. The concept of ambulatory cardiac intervention nurses functioning as dedicated coordinators may be key in the future transition of hospitals to SDD. Ultrasound-guided femoral puncture virtually eliminated relevant femoral access-site complications in our cohort and should therefore be a prerequisite for SDD.

Non-invasive detection of slow conduction with cardiac magnetic resonance imaging for ventricular tachycardia ablation

AIMS

Non-invasive myocardial scar characterization with cardiac magnetic resonance (CMR) has been shown to accurately identify conduction channels and can be an important aid for ventricular tachycardia (VT) ablation. A new mapping method based on targeting deceleration zones (DZs) has become one of the most commonly used strategies for VT ablation procedures. The aim of the study was to analyse the capability of CMR to identify DZs and to find predictors of arrhythmogenicity in CMR channels.

METHODS AND RESULTS

Forty-four consecutive patients with structural heart disease and VT undergoing ablation after CMR at a single centre (October 2018 to July 2021) were included (mean age, 64.8 ± 11.6 years; 95.5% male; 70.5% with ischaemic heart disease; a mean ejection fraction of 32.3 ± 7.8%). The characteristics of CMR channels were analysed, and correlations with DZs detected during isochronal late activation mapping in both baseline maps and remaps were determined. Overall, 109 automatically detected CMR channels were analysed (2.48 ± 1.15 per patient; length, 57.91 ± 63.07 mm; conducting channel mass, 2.06 ± 2.67 g; protectedness, 21.44 ± 25.39 mm). Overall, 76.1% of CMR channels were associated with a DZ. A univariate analysis showed that channels associated with DZs were longer [67.81 ± 68.45 vs. 26.31 ± 21.25 mm, odds ratio (OR) 1.03, P = 0.010], with a higher border zone (BZ) mass (2.41 ± 2.91 vs. 0.87 ± 0.86 g, OR 2.46, P = 0.011) and greater protectedness (24.97 ± 27.72 vs. 10.19 ± 9.52 mm, OR 1.08, P = 0.021).

CONCLUSION

Non-invasive detection of targets for VT ablation is possible with CMR. Deceleration zones found during electroanatomical mapping accurately correlate with CMR channels, especially those with increased length, BZ mass, and protectedness.

Post-Ablation cardiac Magnetic resonance to assess Ventricular Tachycardia recurrence (PAM-VT study)

AIMS

Conducting channels (CCs) detected by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) are related to ventricular tachycardia (VT). The aim of this work was to study the ability of post-ablation LGE-CMR to evaluate ablation lesions.

METHODS AND RESULTS

This is a prospective study of consecutive patients referred for a scar-related VT ablation. LGE-CMR was performed 6-12 months prior to ablation and 3-6 months after ablation. Scar characteristics of pre- and post-ablation LGE-CMR were compared. During the study period (March 2019-April 2021), 61 consecutive patients underwent scar-related VT ablation after LGE-CMR. Overall, 12 patients were excluded (4 had poor-quality LGE-CMR, 2 died before post-ablation LGE-CMR, and 6 underwent post-ablation LGE-CMR 12 months after ablation). Finally, 49 patients (age: 65.5 ± 9.8 years, 97.9% male, left ventricular ejection fraction: 34.8 ± 10.4%, 87.7% ischaemic cardiomyopathy) were included. Post-ablation LGE-CMR showed a decrease in the number (3.34 ± 1.03 vs. 1.6 ± 0.2; P < 0.0001) and mass (8.45 ± 1.3 vs. 3.5 ± 0.6 g; P < 0.001) of CCs. Arrhythmogenic CCs disappeared in 74.4% of patients. Dark core was detected in 75.5% of patients, and its presence was not related to CC reduction (52.2 ± 7.4% vs. 40.8 ± 10.6%, P = 0.57). VT recurrence after one year follow-up was 16.3%. The presence of two or more channels in the post-ablation LGE-CMR was a predictor of VT recurrence (31.82% vs. 0%, P = 0.0038) with a sensibility of 100% and specificity of 61% (area under the curve 0.82). In the same line, a reduction of CCs < 55% had sensibility of 100% and specificity of 61% (area under the curve 0.83) to predict VT recurrence.

CONCLUSION

Post-ablation LGE-CMR is feasible, and a reduction in the number of CCs is related with lower risk of VT recurrence. The dark core was not present in all patients. A decrease in VT substrate was also observed in patients without a dark core area in the post-ablation LGE-CMR.

Myocardial scarring and recurrence of ventricular arrhythmia in patients surviving an out-of-hospital cardiac arrest

INTRODUCTION

Prediction of recurrent ventricular arrhythmia (VA) in survivors of an out-of-hospital cardiac arrest (OHCA) is important, but currently difficult. Risk of recurrence may be related to presence of myocardial scarring assessed with late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). Our study aims to characterize myocardial scarring as defined by LGE-CMR in survivors of a VA-OHCA and investigate its potential role in the risk of new VA events.

METHODS

Between 2015 and 2022, a total of 230 VA-OHCA patients without ST-segment elevation myocardial infarction had CMR before implantable cardioverter-defibrillator implantation for secondary prevention at Copenhagen University Hospital, Rigshospitalet, and Hospital Clínic, University of Barcelona, of which n = 170 patients had a conventional (no LGE protocol) CMR and n = 60 patients had LGE-CMR (including LGE protocol). Scar tissue including core, border zone (BZ) and BZ channels were automatically detected by specialized investigational software in patients with LGE-CMR. The primary endpoint was recurrent VA.

RESULTS

After exclusion, n = 52 VA-OHCA patients with LGE-CMR and a mean left ventricular ejection fraction of 49 ± 16% were included, of which 18 (32%) patients reached the primary endpoint of VA. Patients with recurrent VA in exhibited greater scar mass, core mass, BZ mass, and presence of BZ channels compared with patients without recurrent VA. The presence of BZ channels identified patients with recurrent VA with 67% sensitivity and 85% specificity (area under the ROC curve (AUC) 0.76; 95% CI: 0.63-0.89; p < .001) and was the strongest predictor of the primary endpoint.

CONCLUSIONS

The presence of BZ channels was the strongest predictor of recurrent VA in patients with an out of-hospital cardiac arrest and LGE-CMR.

Magnetic resonance detection of advanced atrial cardiomyopathy increases the risk for atypical atrial flutter occurrence following atrial fibrillation ablation

AIMS

Recurrence of arrhythmia after catheter ablation of atrial fibrillation (AF) in the form of atypical atrial flutter (AFL) is common among a significant number of patients and often requires redo ablation with limited success rates. Identifying patients at high risk of AFL after AF ablation could aid in patient selection and personalized ablation approach. The study aims to assess the relationship between pre-existing atrial cardiomyopathy and the occurrence of AFL following AF ablation.

METHODS AND RESULTS

We analysed a cohort of 1007 consecutive AF patients who underwent catheter ablation and were included in a prospective registry. Patients who did not have baseline cardiac magnetic resonance imaging and late gadolinium enhancement (LGE-CMR) or did not experience any recurrences were excluded. A total of 166 patients were included gathering 56 patients who underwent re-ablation due to AFL recurrences and 110 patients who underwent re-ablation due to AF recurrences (P = 0.11). A multiparametric assessment of atrial cardiomyopathy was based on basal LGE-CMR, including left atrial (LA) volume, LA sphericity, and global and segmental LA fibrosis using semiautomated post-processing software. Out of the initial cohort of 1007 patients, AFL and AF occurred in 56 and 110 patients, respectively. An age higher than 65 [odds ratio (OR) = 5.6, 95% confidence interval (CI): 2.2-14.4], the number of previous ablations (OR = 3.0, 95% CI: 1.2-7.8), and the management of ablation lines in the index procedure (OR = 2.5, 95% CI: 1.0-6.3) were independently associated with AFL occurrence. Furthermore, several characteristics assessed by LGE-CMR were identified as independent predictors of AFL recurrence after the index ablation for AF, such as enhanced LA sphericity (OR = 1.3, 95% CI: 1.1-1.6), LA global fibrosis (OR = 1.03, 95% CI: 1.01-1.07), and increased fibrosis in the lateral wall (OR = 1.03, 95% CI: 1.01-1.04).

CONCLUSION

Advanced atrial cardiomyopathy assessed by LGE-CMR, such as increased LA sphericity, global LA fibrosis, and fibrosis in the lateral wall, is independently associated with arrhythmia recurrence in the form of AFL following AF ablation.

Management of Ventricular Arrhythmias in Heart Failure

PURPOSE OF REVIEW

Despite substantial progress in medical and device-based heart failure (HF) therapy, ventricular arrhythmias (VA) and sudden cardiac death (SCD) remain a major challenge. Here we review contemporary management of VA in the context of HF with one particular focus on recent advances in imaging and catheter ablation.

RECENT FINDINGS

Besides limited efficacy of antiarrhythmic drugs (AADs), their potentially life-threatening side effects are increasingly acknowledged. On the other hand, with tremendous advances in catheter technology, electroanatomical mapping, imaging, and understanding of arrhythmia mechanisms, catheter ablation has evolved into a safe, efficacious therapy. In fact, recent randomized trials support early catheter ablation, demonstrating superiority over AAD. Importantly, CMR imaging with gadolinium contrast has emerged as a central tool for the management of VA complicating HF: CMR is not only essential for an accurate diagnosis of the underlying entity and subsequent treatment decisions, but also improves risk stratification for SCD prevention and patient selection for ICD therapy. Finally, 3-dimensional characterization of arrhythmogenic substrate by CMR and imaging-guided ablation approaches substantially enhance procedural safety and efficacy. VA management in HF patients is highly complex and should be addressed in a multidisciplinary approach, preferably at specialized centers. While recent evidence supports early catheter ablation of VA, an impact on mortality remains to be demonstrated. Moreover, risk stratification for ICD therapy may have to be reconsidered, taking into account imaging, genetic testing, and other parameters beyond left ventricular function.

Stepwise application of ECG and electrogram-based criteria to ensure electrical resynchronization with left bundle branch pacing

AIMS

To define a stepwise application of left bundle branch pacing (LBBP) criteria that will simplify implantation and guarantee electrical resynchronization. Left bundle branch pacing has emerged as an alternative to biventricular pacing. However, a systematic stepwise criterion to ensure electrical resynchronization is lacking.

METHODS AND RESULTS

A cohort of 24 patients from the LEVEL-AT trial (NCT04054895) who received LBBP and had electrocardiographic imaging (ECGI) at 45 days post-implant were included. The usefulness of ECG- and electrogram-based criteria to predict accurate electrical resynchronization with LBBP were analyzed. A two-step approach was developed. The gold standard used to confirm resynchronization was the change in ventricular activation pattern and shortening in left ventricular activation time, assessed by ECGI. Twenty-two (91.6%) patients showed electrical resynchronization on ECGI. All patients fulfilled pre-screwing requisites: lead in septal position in left-oblique projection and W paced morphology in V1. In the first step, presence of either right bundle branch conduction delay pattern (qR or rSR in V1) or left bundle branch capture Plus (QRS ≤120 ms) resulted in 95% sensitivity and 100% specificity to predict LBBP resynchronization, with an accuracy of 95.8%. In the second step, the presence of selective capture (100% specificity, only 41% sensitivity) or a spike-R <80 ms in non-selective capture (100% specificity, sensitivity 46%) ensured 100% accuracy to predict resynchronization with LBBP.

CONCLUSION

Stepwise application of ECG and electrogram criteria may provide an accurate assessment of electrical resynchronization with LBBP (Graphical abstract).

Quantification of right atrial fibrosis by cardiac magnetic resonance: verification of the method to standardize thresholds

INTRODUCTION AND OBJECTIVES

Late gadolinium-enhanced cardiac magnetic resonance (LGE-CMR) allows noninvasive detection of left atrial fibrosis in patients with atrial fibrillation (AF). However, whether the same methodology can be used in the right atrium (RA) remains unknown. Our aim was to define a standardized threshold to characterize RA fibrosis in LGE-CMR.

METHODS

A 3 Tesla LGE-CMR was performed in 53 individuals; the RA was segmented, and the image intensity ratio (IIR) calculated for the RA wall using 1 557 767 IIR pixels (40 994±10 693 per patient). The upper limit of normality of the IIR (mean IIR+2 standard deviations) was estimated in healthy volunteers (n=9), and patients who had undergone previous typical atrial flutter ablation (n=9) were used to establish the dense scar threshold. Paroxysmal and persistent AF patients (n=10 each) were used for validation. IIR values were correlated with a high-density bipolar voltage map in 15 patients undergoing AF ablation.

RESULTS

The upper normality limit (total fibrosis threshold) in healthy volunteers was set at an IIR = 1.21. In the postablation group, 60% of the maximum IIR pixel (dense fibrosis threshold) was calculated as IIR = 1.29. Endocardial bipolar voltage showed a weak but significant correlation with IIR. The overall accuracy between the electroanatomical map and LGE-CMR to characterize fibrosis was 56%.

CONCLUSIONS

An IIR > 1.21 was determined to be the threshold for the detection of right atrial fibrosis, while an IIR > 1.29 differentiates interstitial fibrosis from dense scar. Despite differences between the left and right atria, fibrosis could be assessed with LGE-CMR using similar thresholds in both chambers.

Scar conducting channel characterization to predict arrhythmogenicity during ventricular tachycardia ablation

AIMS

Heterogeneous tissue channels (HTCs) detected by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) are related to ventricular arrhythmias, but there are few published data about their arrhythmogenic characteristics.

METHODS AND RESULTS

We enrolled 34 consecutive patients with ischaemic and non-ischaemic cardiomyopathy who were referred for ventricular tachycardia (VT) ablation. LGE-CMR was performed prior to ablation, and the HTCs were analyzed. Arrhythmogenic HTCs linked to induced VT were identified during the VT ablation procedure. The characteristics of arrhythmogenic HTCs were compared with those of non-arrhythmogenic HTCs. Three patients were excluded due to low-quality LGE-CMR images. A total of 87 HTCs were identified on LGE-CMR in 31 patients (age:63.8 ± 12.3 years; 96.8% male; left ventricular ejection fraction: 36.1 ± 10.7%). Of the 87 HTCs, only 31 were considered arrhythmogenic because of their relation to a VT isthmus. The HTCs related to a VT isthmus were longer [64.6 ± 49.4 vs. 32.9 ± 26.6 mm; OR: 1.02; 95% CI: (1.01-1.04); P < 0.001] and had greater mass [2.5 ± 2.2 vs. 1.2 ± 1.2 grams; OR: 1.62; 95% CI: (1.18-2.21); P < 0.001], a higher degree of protectedness [26.19 ± 19.2 vs. 10.74 ± 8.4; OR 1.09; 95% CI: (1.04-1.14); P < 0.001], higher transmurality [number of wall layers with CCs: 3.8 ± 2.4 vs. 2.4 ± 2.0; OR: 1.31; 95% CI: (1.07-1.60); P = 0.008] and more ramifications [3.8 ± 2.0 vs. 2.7 ± 1.1; OR: 1.59; 95% CI: (1.15-2.19); P = 0.002] than non-arrhythmogenic HTCs. Multivariate logistic regression analysis revealed that protectedness was the strongest predictor of arrhythmogenicity.

CONCLUSION

The protectedness of an HTC identified by LGE-CMR is strongly related to its arrhythmogenicity during VT ablation.

Predictive value of late gadolinium enhancement cardiovascular magnetic resonance in patients with persistent atrial fibrillation: dual-centre validation of a standardized method

Aims

With recurrence rates up to 50% after pulmonary vein isolation (PVI) in persistent atrial fibrillation (AF), predictive tools to improve patient selection are needed. Patient selection based on left atrial late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) has been proposed previously (UTAH-classification). However, this approach has not been widely established, in part owed to the lack of standardization of the LGE quantification method. We have recently established a standardized LGE-CMR method enabling reproducible LGE-quantification. Here, the ability of this method to predict outcome after PVI was evaluated.

Methods and results

This dual-centre study (n = 219) consists of a prospective derivation cohort (n = 37, all persistent AF) and an external validation cohort (n = 182; 66 persistent, 116 paroxysmal AF). All patients received an LGE-CMR prior to first-time PVI-only ablation. LGE was quantified based on the signal-intensity-ratio relative to the blood pool, applying a uniform LGE-defining threshold of >1.2.  In patients with persistent AF in the derivation cohort, left atrial LGE-extent above a cut-off value of 12% was found to best predict relevant low-voltage substrate (≥2 cm two with <0.5 mV during sinus rhythm) and arrhythmia-free survival 12 months post-PVI. When applied to the external validation cohort, this cut-off value was also predictive of arrhythmia-free survival for both, the total cohort and the subgroup with persistent AF (LGE < 12%: 80% and 76%; LGE > 12%: 55% and 44%; P = 0.007 and P = 0.029, respectively).

Conclusion

This dual-centre study established and validated a standardized, reproducible LGE-CMR method discriminating PVI responders from non-responders, which may improve choice of therapeutic approach or ablation strategy for patients with persistent AF.

Arrhythmic risk in single or recurrent episodes of unexplained syncope with complete bundle branch block

INTRODUCTION AND OBJECTIVES

Patients with a single syncopal episode (SSE) and complete bundle branch block (cBBB) are frequently managed more conservatively than patients with recurrent episodes (RSE). The objective of this study was to analyze if there are differences between patients with single or recurrent unexplained syncope and cBBB in arrhythmic risk, the diagnostic yield of tests, and clinical outcomes.

METHODS

Cohort study of consecutive patients with unexplained syncope and cBBB with a median follow-up time of 3 years. The patients were evaluated via a stepwise workup protocol based on electrophysiological study (EPS) and long-term follow-up with an implantable cardiac monitor.

RESULTS

Of the 503 patients included in the study, 238 (47.3%) had had only 1 syncopal episode. The risk of an arrhythmic syncope was similar in both groups (58.8% in SSE vs 57.0% in RSE; P=.68), also after adjustment for possible confounding variables (HR, 1.06; 95%CI, 0.81-1.38; P=.674). No significant differences between the groups were found in the EPS results and implantable cardiac monitor diagnostic yield. A total of 141 (59.2%) patients with SSE and 154 (58.1%) patients with RSE required cardiac device implantation (P=.797). After appropriate treatment, 35 (7%) patients had recurrence of syncope. The recurrence rate and mortality were also similar in both groups.

CONCLUSIONS

Patients with cBBB and unexplained syncope are at high risk of an arrhythmic etiology, even after the first syncopal episode. Patients with SSE and RSE have a similar arrhythmic risk and similar outcomes, and therefore there is no clinical justification for not managing them in the same manner.

Conduction System Pacing vs Biventricular Pacing in Heart Failure and Wide QRS Patients: LEVEL-AT Trial

BACKGROUND

Conduction system pacing (CSP) has emerged as an alternative to biventricular pacing (BiVP). Randomized studies comparing both therapies are scarce and do not include left bundle branch pacing.

OBJECTIVES

This study aims to compare ventricular resynchronization achieved by CSP vs BiVP in patients with cardiac resynchronization therapy indication.

METHODS

LEVEL-AT (Left Ventricular Activation Time Shortening with Conduction System Pacing vs Biventricular Resynchronization Therapy) was a randomized, parallel, controlled, noninferiority trial. Seventy patients with cardiac resynchronization therapy indication were randomized 1:1 to BiVP or CSP, and followed up for 6 months. Crossover was allowed when primary allocation procedure failed. Primary endpoint was the change in left ventricular activation time, measured using electrocardiographic imaging. Secondary endpoints were left ventricular reverse remodeling and the combined endpoint of heart failure hospitalization or death at 6-month follow-up.

RESULTS

Thirty-five patients were allocated to each group. Eight (23%) patients crossed over from CSP to BiVP; 2 patients (6%) crossed over from BiVP to CSP. Electrocardiographic imaging could not be performed in 2 patients in each group. A similar decrease in left ventricular activation time was achieved by CSP and BiVP (-28 ± 26 ms vs -21 ± 20 ms, respectively; mean difference -6.8 ms; 95% CI: -18.3 ms to 4.6 ms; P < 0.001 for noninferiority). Both groups showed a similar change in left ventricular end-systolic volume (-37 ± 59 mL CSP vs -30 ± 41 mL BiVP; mean difference: -8 mL; 95% CI: -33 mL to 17 mL; P = 0.04 for noninferiority) and similar rates of mortality or heart failure hospitalizations (2.9% vs 11.4%, respectively) (P = 0.002 for noninferiority).

CONCLUSIONS

Similar degrees of cardiac resynchronization, ventricular reverse remodeling, and clinical outcomes were attained by CSP as compared to BiVP. CSP could be a feasible alternative to BiVP. (LEVEL-AT [Left Ventricular Activation Time Shortening With Conduction System Pacing vs Biventricular Resynchronization Therapy]; NCT04054895).

Progressive and Simultaneous Right and Left Atrial Remodeling Uncovered by a Comprehensive Magnetic Resonance Assessment in Atrial Fibrillation

Background Left atrial structural remodeling contributes to the arrhythmogenic substrate of atrial fibrillation (AF), but the role of the right atrium (RA) remains unknown. Our aims were to comprehensively characterize right atrial structural remodeling in AF and identify right atrial parameters predicting recurrences after ablation. Methods and Results A 3.0 T late gadolinium enhanced-cardiac magnetic resonance was obtained in 109 individuals (9 healthy volunteers, 100 patients with AF undergoing ablation). Right and left atrial volume, surface, and sphericity were quantified. Right atrial global and regional fibrosis burden was assessed with validated thresholds. Patients with AF were systematically followed after ablation for recurrences. Progressive right atrial dilation and an increase in sphericity were observed from healthy volunteers to patients with paroxysmal and persistent AF; fibrosis was similar among the groups. The correlation between parameters recapitulating right atrial remodeling was mild. Subsequently, remodeling in both atria was compared. The RA was larger than the left atrium (LA) in all groups. Fibrosis burden was higher in the LA than in the RA of patients with AF, whereas sphericity was higher in the LA of patients with persistent AF only. Fibrosis, volume, and surface of the RA and LA, but not sphericity, were strongly correlated. Tricuspid regurgitation predicted right atrial volume and shape, whereas diabetes was associated with right atrial fibrosis burden; sex and persistent AF also predicted right atrial volume. Fibrosis in the RA was mostly located in the inferior vena cava-RA junction. Only right atrial sphericity is significantly associated with AF recurrences after ablation (hazard ratio, 1.12 [95% CI, 1.01-1.25]). Conclusions AF progression associates with right atrial remodeling in parallel with the LA. Right atrial sphericity yields prognostic significance after ablation.

Cardiac injury before and after COVID-19. A longitudinal MRI study

Background

Recent MRI-based studies have raised great concern about frequent cardiac involvement even in mild or asymptomatic COVID-19. However, while signs of myocardial injury were found in large proportions of patients after COVID-19, all studies published to date lack baseline imaging and are therefore unable to discriminate between pre-existing and COVID-19-induced injury.

Purpose

In this longitudinal study, we aimed to assess the true cardiac impact of COVID-19 based on pre- and post-COVID-19 late gadolinium enhancement (LGE)-MRI.

Methods

A prospective registry of patients with serial LGE-MRIs was screened for patients with documented SARS-COV-2 infection after cardiac LGE-MRI. Eligible patients then received a post-COVID-19 LGE-MRI using the same scanner and sequence as in the pre-COVID-19 MRI. Inversion recovery prepared T1-weighted gradient echo sequences were acquired in sinus rhythm using ECG gating and a free-breathing 3D navigator, 15–20 minutes after administering an intravenous bolus of 0.2 mmol/kg of gadobutrol. A TI scout sequence was used in order to determine the optimal TI that nullified the left ventricular myocardial signal. The presence of LGE was independently assessed qualitatively by two experienced investigators blinded to patient information. For quantitative analyses a 3D-reconstruction of the left ventricle was performed using ADAS-3D software. LGE was then automatically quantified based on a prespecified signal intensity threshold of ≥3 SD above the mean of a remote non-enhanced myocardial region.

Results

Pre- and post-COVID LGE-MRI from 31 patients with cardiovascular risk factors that had recovered from mild to moderate COVID-19 (23% hospitalised) were analysed. At a median of 5 months post-COVID-19, LGE-lesions indicative of myocardial injury were encountered in 15 out of 31 patients (48%), which is in line with previous reports. However, intraindividual comparison with the pre-COVID-19 MRI reveiled all of these lesions as pre-existing and thus not COVID-19-related. Quantitative analysis detected no increase in the size of individual LGE-lesions, nor in the global left ventricular LGE-extent. There was no difference in any functional or structural parameter between pre- and post-COVID-19 MRI.

Conclusion

This longitudinal study in a cohort of patients considered at high risk of cardiac involvement, did not find any evidence for COVID-19-induced myocardial injury. The complete absence of de novo LGE lesions in this cohort is reassuring and indicates that cardiac sequelae of COVID-19 are rare and certainly not as common as previously suggested.

Funding Acknowledgement

Type of funding sources: None.

Non-invasive assessment of pulmonary vein isolation durability using late gadolinium enhancement magnetic resonance imaging

AIMS

Electrical reconnection of pulmonary veins (PVs) is considered an important determinant of recurrent atrial fibrillation (AF) after pulmonary vein isolation (PVI). To date, AF recurrences almost automatically trigger invasive repeat procedures, required to assess PVI durability. With recent technical advances, it is becoming increasingly common to find all PVs isolated in those repeat procedures. Thus, as ablation of extra-PV targets has failed to show benefit in randomized trials, more and more often these highly invasive procedures are performed only to rule out PV reconnection. Here we aim to define the ability of late gadolinium enhancement (LGE)-magnetic resonance imaging (MRI) to rule out PV reconnection non-invasively.

METHODS AND RESULTS

This study is based on a prospective registry in which all patients receive an LGE-MRI after AF ablation. Included were all patients that-after an initial PVI and post-ablation LGE-MRI-underwent an invasive repeat procedure, which served as a reference to determine the predictive value of non-invasive lesion assessment by LGE-MRI.: 152 patients and 304 PV pairs were analysed. LGE-MRI predicted electrical PV reconnection with high sensitivity (98.9%) but rather low specificity (55.6%). Of note, LGE lesions without discontinuation ruled out reconnection of the respective PV pair with a negative predictive value of 96.9%, and patients with complete LGE lesion sets encircling all PVs were highly unlikely to show any PV reconnection (negative predictive value: 94.4%).

CONCLUSION

LGE-MRI has the potential to guide selection of appropriate candidates and planning of the ablation strategy for repeat procedures and may help to identify patients that will not benefit from a redo-procedure if no ablation of extra-PV targets is intended.

Ventricular Tachycardia Ablation Guided by Functional Substrate Mapping: Practices and Outcomes

Catheter ablation of ventricular tachycardia has demonstrated its important role in the treatment of ventricular tachycardia in patients with structural cardiomyopathy. Conventional mapping techniques used to define the critical isthmus, such as activation mapping and entrainment, are limited by the non-inducibility of the clinical tachycardia or its poor hemodynamic tolerance. To overcome these limitations, a voltage mapping strategy based on bipolar electrograms peak to peak analysis was developed, but a low specificity (30%) for VT isthmus has been described with this approach. Functional mapping strategy relies on the analysis of the characteristics of the electrograms but also their propagation patterns and their response to extra-stimulus or alternative pacing wavefronts to define the targets for ablation. With this review, we aim to summarize the different functional mapping strategies described to date to identify ventricular arrhythmic substrate in patients with structural heart disease.

Orthogonal high-density mapping with ventricular tachycardia isthmus analysis vs. pure substrate ventricular tachycardia ablation: A case-control study

Background

Substrate-based ablation has become a successful technique for ventricular tachycardia (VT) ablation. High-density (HD) mapping catheters provide high-resolution electroanatomical maps and better discrimination of local abnormal electrograms. The HD Grid Mapping Catheter is an HD catheter with the ability to map orthogonal signals on top of conventional bipolar signals, which could provide better discrimination of the arrhythmic substrate. On the other hand, conventional mapping techniques, such as activation mapping, when possible, help to identify the isthmus of the tachycardia.

Aim

The purpose of this study was to compare clinical outcomes after using two different VT ablation strategies: one based on extensive mapping with the HD Grid Mapping Catheter, including VT isthmus analysis, and the other based on pure substrate ablation.

Methods

Forty consecutive patients undergoing VT ablation with extensive HD mapping method in the hospital clinic (November 2018–November 2019) were included. Clinical outcomes were compared with a historical cohort of 26 consecutive patients who underwent ablation using a scar dechanneling technique before 2018.

Results

The density of mapping points was higher in the extensive mapping group (2370.24 ± 920.78 vs. 576.45 ± 294.46; p < 0.001). After 1 year of follow-up, VT recurred in 18.4% of patients in the extensive mapping group vs. 34.6% of patients in the historical control group (p = 0.14), with a significantly greater reduction of VT burden: VT episodes (81.7 ± 7.79 vs. 43.4 ± 19.9%, p < 0.05), antitachycardia pacing (99.45 ± 2.29 vs. 33.9 ± 102.5%, p < 0.001), and implantable cardioverter defibrillator (ICD) shocks (99 ± 4.5 vs. 64.7 ± 59.9%, p = 0.02).

Conclusion

The use of a method based on extensive mapping with the HD Grid Mapping Catheter and VT isthmus analysis allows better discrimination of the arrhythmic substrate and could be associated with a greater decrease in VT burden.

Late Potential Abolition in Ventricular Tachycardia Ablation

Ventricular tachycardia (VT) substrate-based ablation has become the gold standard treatment for patients with structural heart disease-related VT. VT is linked to re-entry in relation to myocardial scarring, with areas of conduction block (core scar) and of slow conduction (border zone). Slow conduction areas can be detected in sinus rhythm as late potentials (LPs). LP abolition has been shown to be the best end point to avoid long-term recurrences. Our study aimed to analyze the challenges of LP abolition and the predictors of failure. We analyzed 169 consecutive patients with structural heart disease (61% ischemic cardiomyopathy, left ventricular ejection fraction: 37 ± 13%) who underwent VT ablation between 2013 and 2018. A preprocedural clinical evaluation, including cardiac magnetic resonance, was done in 66% of patients. Electroanatomical mapping with the identification of LPs was performed in all patients. Noninducibility was achieved in 71% (119), and complete LP abolition was achieved in 61% (103) of patients. Incomplete LP abolition was a powerful predictor of VT recurrence (67% vs 33%, hazard ratio 3.19 [2.1 to 4.7]; p <0.001). Lack of use of a high-density mapping catheter (odds ratio 6.2, 1.2 to 38.1; p = 0.028), the septal substrate (odds ratio 9.34, 2.27 to 38.4; p = 0.002), and larger left ventricular mass (190 ± 58 g vs 156 ± 46 g, p = 0.002) were predictors of incomplete LP abolition. The main reasons that contributed to unsuccessful LP abolition were anatomic obstacles (such as the conduction system) and large extension of the LP area. In conclusion, incomplete LP abolition is related to VT recurrence. Lack of use of a high-density mapping catheter, the septal substrate, and larger left ventricular mass are related to incomplete LP abolition.

Septal flash correction with His-Purkinje pacing predicts echocardiographic response in resynchronization therapy

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): Grant of the Catalan Society of Cardiology, 2019; Research Grant Josep Font 2019, Hospital Clínic de Barcelona

His-Purkinje conduction system pacing (HPCSP) has been proposed as an alternative to cardiac resynchronization therapy (CRT); however, no predictors of echocardiographic response have been described. Septal flash (SF) is a marker of intraventricular dyssynchrony.

Methods

The study aimed to analyze whether HPCSP corrects SF in patients with CRT indication, and if correction of SF predicts echocardiographic response. Prospective observational study (n=30). Left ventricular ejection fraction (LVEF) was measured with echocardiography at baseline and at 6-month follow-up. Echocardiographic response was defined as increase in 5 points LVEF. ECG Imaging was performed in 2 patients to validate ventricular activation shortening and to study the basal and HPCSP activation pattern.

Results

HPCSP shortened QRS duration by 48±21ms and SF was significantly decreased (baseline 3.6±2.2mm vs HPCSP 1.5±1.5mm p&lt;0.0001) (Fig.1). At 6-months, mean LVEF improvement was 8.6% ± 8.7% and 64% of patients were responders. There was a significant correlation between SF correction and increased LVEF (r=0.61, p=0.004). A correction of &gt;1.5mm had 81% sensitivity and 80% specificity to predict echocardiographic response (area under curve 0.86, p=0.019).

Conclusion

HPCSP improves intraventricular dyssynchrony and results in 64% echocardiographic responders at 6-month follow-up. Dyssynchrony improvement with SF correction may predict echocardiographic response at 6-month follow-up (Fig.2.).

Ablation Lesion Assessment with MRI

Late gadolinium enhancement (LGE) MRI is capable of detecting not only native cardiac fibrosis, but also ablation-induced scarring. Thus, it offers the unique opportunity to assess ablation lesions non-invasively. In the atrium, LGE-MRI has been shown to accurately detect and localise gaps in ablation lines. With a negative predictive value close to 100% it can reliably rule out pulmonary vein reconnection non-invasively and thus may avoid unnecessary invasive repeat procedures where a pulmonary vein isolation only approach is pursued. Even LGE-MRI-guided repeat pulmonary vein isolation has been demonstrated to be feasible as a standalone approach. LGE-MRI-based lesion assessment may also be of value to evaluate the efficacy of ventricular ablation. In this respect, the elimination of LGE-MRI-detected arrhythmogenic substrate may serve as a potential endpoint, but validation in clinical studies is lacking. Despite holding great promise, the widespread use of LGE-MRI is still limited by the absence of standardised protocols for image acquisition and post-processing. In particular, reproducibility across different centres is impeded by inconsistent thresholds and internal references to define fibrosis. Thus, uniform methodological and analytical standards are warranted to foster a broader implementation in clinical practice.

Sex-Related Differences in Patients With Unexplained Syncope and Bundle Branch Block: Lower Risk of AV Block and Lesser Need for Cardiac Pacing in Women

Objective

To analyze if there are sex-related differences in patients with unexplained syncope and bundle branch block (BBB).

Background

Despite increasing awareness that sex is a major determinant of the incidence, etiology, and the outcomes of different arrhythmias, no studies have examined differences in presentation and outcomes between men and women with syncope and BBB.

Methods

Cohort study of consecutive patients with unexplained syncope and BBB was included from January 2010 to January 2021 with a median follow-up time of 3.4 years [interquartile range (IQR) 1.7–6.0 years]. They were evaluated by a stepwise workup protocol based on electrophysiological study (EPS) and long-term follow-up with an implantable cardiac monitor (ICM).

Results

Of the 443 patients included in the study, 165 (37.2%) were women. Compared with men, women had less diabetes (25.5 vs. 39.9%, p = 0.002) and less history of ischemic heart disease (IHD; 13.3 vs. 25.9%, p = 0.002). Left bundle branch block (LBBB) was more frequent in women (55.2 vs. 27.7%, p < 0.001) while right bundle branch block (RBBB) was more frequent in men (41.5 vs. 67.7%, p < 0.001). His to ventricle (HV) interval in the EPS was shorter in women (58 ms [IQR 52–71] vs. 60 ms [IQR 52–73], p = 0.035) and less women had an HV interval longer than 70 ms (28.5 vs. 38.1%, p = 0.039), however, EPS and ICM offered a similar diagnostic yield in both sexes (40.6 vs. 48.9% and 48.4% vs. 51.1%, respectively). Women had a lower risk of developing atrioventricular block (AVB) (adjusted odds ratio [OR] 0.44–95% CI 0.26–0.74, p = 0.002) and of requiring permanent pacemaker implantation (adjusted hazard ratio [HR] 0.72–95% CI: 0.52–0.99, p = 0.046). The mortality rate was lower in women (4.5 per 100 person-years [95% CI 3.1–6.4 per 100 person-years] vs. 7.3 per 100 person-years [95% CI 5.9–9.1 per 100 person-years]).

Conclusions

Compared to men, women with unexplained syncope and BBB have a lower risk of AVB and of requiring cardiac pacing. A stepwise diagnostic approach has a similar diagnostic yield in both sexes, and it seems appropriate to guide the treatment and avoid unnecessary pacemaker implantation, especially in women.

Cardiac Magnetic Resonance for Ventricular Tachycardia Ablation and Risk Stratification

Ventricular tachycardia is the most frequent cause of sudden cardiovascular death in patients with structural heart disease. Radiofrequency ablation is the treatment cornerstone in this population. Main mechanism for structural heart disease-related ventricular tachycardia is re-entry due to presence of slow conduction area within the scar tissue. Electroanatomical mapping with high density catheters can elucidate the presence of both scar (voltage maps) and slow conduction (activation maps). Despite the technological improvements recurrence rate after ventricular tachycardia ablation is high. Cardiac magnetic resonance has demonstrated to be useful to define the location of the scar tissue in endocardium, midmyocardium and/or epicardial region. Furthermore, recent studies have shown that cardiac magnetic resonance can analyse in detail the ventricular tachycardia substrate in terms of core scar and border zone tissue. This detailed tissue analysis has been proved to have good correlation with slow conduction areas and ventricular tachycardia isthmuses in electroanatomical maps. This review will provide a summary of the current role of cardiac magnetic resonance in different scenarios related with ventricular tachycardia in patients with structural heart disease, its limitations and the future perspectives.

Non-invasive isthmus identification of complex arrhythmias in congenital heart disease

Sustained re-entrant tachyarrhythmias treatment has become pivotal in the grown-up congenital heart patients clinical management. Cardiac LGE-MRI tissue characterization integrated with high definition electroanatomic map could allow fast recognition and effective treatment of substrate of tachyarrhythmias. Cardiac LGE-MRI areas were suggestive of post-surgical changes both in atrium and ventricle. High-density electro-anatomical map localized areas of slow conduction identifying conducting isthmuses of re-entrant arrhythmias.

Late gadolinium enhancement-MRI determines definite lesion formation most accurately at 3 months post ablation compared to later time points

AIMS

Neither the long-term development of ablation lesions nor the capability of late gadolinium enhancement (LGE)-MRI to detect ablation-induced fibrosis at late stages of scar formation have been defined. We sought to assess the development of atrial ablation lesions over time using LGE-MRI and invasive electroanatomical mapping (EAM).

METHODS AND RESULTS

Ablation lesions and total atrial fibrosis were assessed in serial LGE-MRI scans 3 months and >12 months post pulmonary vein (PV) isolation. High-density EAM performed in subsequent repeat ablation procedures served as a reference. Serial LGE-MRI of 22 patients were analyzed retrospectively. The PV encircling ablation lines displayed an average LGE, indicative of ablation-induced fibrosis, of 91.7% ± 7.0% of the circumference at 3 months, but only 62.8% ± 25.0% at a median of 28 months post ablation (p < 0.0001). EAM performed in 18 patients undergoing a subsequent repeat procedure revealed that the consistent decrease in LGE over time was owed to a reduced detectability of ablation-induced fibrosis by LGE-MRI at time-points > 12 months post ablation. Accordingly, the agreement with EAM regarding detection of ablation-induced fibrosis and functional gaps was good for the LGE-MRI at 3 months (κ .74; p < .0001), but only weak for the LGE-MRI at 28 months post-ablation (κ .29; p < .0001).

CONCLUSION

While non-invasive lesion assessment with LGE-MRI 3 months post ablation provides accurate guidance for future redo-procedures, detectability of atrial ablation lesions appears to decrease over time. Thus, it should be considered to perform LGE-MRI 3 months post-ablation rather than at later time-points > 12 months post ablation, like for example, prior to a planned redo-ablation procedure.

Accuracy of left atrial fibrosis detection with cardiac magnetic resonance: correlation of late gadolinium enhancement with endocardial voltage and conduction velocity

AIMS

Myocardial fibrosis is a hallmark of atrial fibrillation (AF) and its characterization could be used to guide ablation procedures. Late gadolinium enhanced-magnetic resonance imaging (LGE-MRI) detects areas of atrial fibrosis. However, its accuracy remains controversial. We aimed to analyse the accuracy of LGE-MRI to identify left atrial (LA) arrhythmogenic substrate by analysing voltage and conduction velocity at the areas of LGE.

METHODS AND RESULTS

Late gadolinium enhanced-magnetic resonance imaging was performed before ablation in 16 patients. Atrial wall intensity was normalized to blood pool and classified as healthy, interstitial fibrosis, and dense scar tissue depending of the resulting image intensity ratio. Bipolar voltage and local conduction velocity were measured in LA with high-density electroanatomic maps recorded in sinus rhythm and subsequently projected into the LGE-MRI. A semi-automatic, point-by-point correlation was made between LGE-MRI and electroanatomical mapping. Mean bipolar voltage and local velocity progressively decreased from healthy to interstitial fibrosis to scar. There was a significant negative correlation between LGE with voltage (r = -0.39, P < 0.001) and conduction velocity (r = -0.25, P < 0.001). In patients showing dilated atria (LA diameter ≥45 mm) the conduction velocity predictive capacity of LGE-MRI was weaker (r = -0.40 ± 0.09 vs. -0.20 ± 0.13, P = 0.02).

CONCLUSIONS

Areas with higher LGE show lower voltage and slower conduction in sinus rhythm. The enhancement intensity correlates with bipolar voltage and conduction velocity in a point-by-point analysis. The performance of LGE-MRI in assessing local velocity might be reduced in patients with dilated atria (LA diameter ≥45).

Ventricular scar channel entrances identified by new wideband cardiac magnetic resonance sequence to guide ventricular tachycardia ablation in patients with cardiac defibrillators

AIMS

Ventricular tachycardia (VT) substrate-based ablation has become a standard procedure. Electroanatomical mapping (EAM) detects scar tissue heterogeneity and define conduction channels (CCs) that are the ablation target. Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) is able to depict CCs and increase ablation success. Most patients undergoing VT ablation have an implantable cardioverter-defibrillator (ICD) that can cause image artefacts in LGE-CMR. Recently wideband (WB) LGE-CMR sequence has demonstrated to decrease these artefacts. The aim of this study is to analyse accuracy of WB-LGE-CMR in identifying the CC entrances.

METHODS AND RESULTS

Thirteen consecutive ICD-patients who underwent VT ablation after WB-LGE-CMR were included. Number and location of CC entrances in three-dimensional EAM and in WB-LGE-CMR reconstruction were compared. Concordance was compared with a historical cohort matched by cardiomyopathy, scar location, and age (26 patients) with LGE-CMR prior to ICD and VT ablation. In WB-CMR group, 101 and 93 CC entrances were identified in EAM and WB-LGE-CMR, respectively. In historical cohort, 179 CC entrances were identified in both EAM and LGE-CMR. The EAM/CMR concordance was 85.1% and 92.2% in the WB and historical group, respectively (P = 0.66). There were no differences in false-positive rate (CC entrances detected in CMR and absent in EAM: 7.5% vs 7.8% in WB vs. conventional CMR, P = 0.92) nor in false-negative rate (CC entrances present in EAM not detected in CMR: 14.9% vs.7.8% in WB vs. conventional CMR, P = 0.23). Epicardial CCs was predictor of poor CMR/EAM concordance (OR 2.15, P = 0.031).

CONCLUSION

Use of WB-LGE-CMR sequence in ICD-patients allows adequate VT substrate characterization to guide VT ablation with similar accuracy than conventional LGE-CMR in patients without an ICD.

Cardiac Resynchronization Therapy Response Is Equalized in Men and Women by Electrical Optimization: PR Matters

OBJECTIVES

This study hypothesized that the shorter intrinsic PR interval observed in women allows a greater degree of fusion with intrinsic conduction, achieving a shorter QRS interval duration and, thus, a better response.

BACKGROUND

Women benefit more from cardiac resynchronization therapy (CRT) than men. However, the reason for this difference remains elusive.

METHODS

A cohort of 180 patients included in the BEST (Fusion based optimization in resynchronization therapy [ECG Optimization of CRT: Evaluation of Mid-Term Response]; NCT01439529) study were retrospectively analyzed. Patients were initially randomized to either nonoptimized CRT (NON-OPT group; n = 89) or electrocardiographically optimized CRT based on the fusion-optimized intervals (FOI) method (FOI group; n = 91). Echocardiographic response was defined as a >15% decrease in left ventricular end-systolic volume at the 12-month follow-up.

RESULTS

The basal PR interval was shorter in women as compared to men. In the NON-OPT group, CRT resulted in a shorter paced QRS interval in women than in men (134 ± 21 ms vs. 151 ± 21 ms, respectively; p = 0.003, 95% confidence interval [CI]: -27 to -5.6) and better response in women than in men: 70.4% vs. 46.4%, respectively (odds ratio: 0.37; p = 0.04; 95% CI: 0.14 to 0.97). There were no differences in paced QRS interval duration (126 ± 13 ms vs. 129 ± 17 ms; p = 0.47) or response between women and men in the FOI group (68% vs. 70.5%; odds ratio: 1.12; p = 0.82; 95% CI: 0.41 to 3.07). FOI extended the atrioventricular interval to obtain the best fusion; the atrioventricular intervals tended to require greater extension in men than in women (22 ± 33 ms vs. 8 ± 28 ms, respectively; p = 0.07).

CONCLUSIONS

Women had a shorter PR interval, which was associated with a shorter QRS interval and better response to CRT. The difference in QRS interval duration and response between men and women did not persist when CRT was optimized using fusion with intrinsic conduction (FOI programming).

Cardiac magnetic resonance to predict recurrences after ventricular tachycardia ablation: septal involvement, transmural channels, and left ventricular mass

AIMS

Ventricular tachycardia (VT) substrate-based ablation has an increasing role in patients with structural heart disease-related VT. VT is linked to re-entry in relation to myocardial scarring with areas of conduction block (core scar) and areas of slow conduction [border zone (BZ)]. VT substrate can be analysed by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). Our study aims to analyse the role of LGE-CMR in identifying predictors of VT recurrence after ablation.

METHODS AND RESULTS

We analysed 110 consecutive patients who underwent VT ablation from 2013 to 2018. All patients underwent a preprocedural LGE-CMR, and in 94 patients (85.5%), the CMR was used to aid the ablation. All LGE-CMR images were semi-automatically processed using dedicated software to detect scarring and conducting channels. After a median follow-up of 2.7 ± 1.6 years, the overall VT recurrence was 41.8% with an implantable cardioverter-defibrillator shock reduction from 43.6% to 28.2% before and after ablation, respectively. The amount of BZ (26.6 ± 13.9 vs. 19.6 ± 9.7 g, P = 0.012), the total amount of scarring (37.1 ± 18.2 vs. 29 ± 16.3 g, P = 0,033), and left ventricular (LV) mass (168.3 ± 53.3 vs. 152.3 ± 46.4 g, P < 0.001) were associated with VT recurrence. LGE septal distribution [62.5% vs. 37.8%; hazard ratio (HR) 1.67 (1.02-3.93), P = 0.044], channels with transmural path [66.7% vs. 31.4%, HR 3.25 (1.70-6.23), P < 0.001], and midmural channels [54.3% vs. 27.6%, HR 2.49 (1.21-5.13), P = 0.013] were related with VT recurrence. Multivariate analysis showed that the presence of septal LGE [HR 3.67 (1.60-8.38), P = 0.002], transmural channels [HR 2.32 (1.15-4.72), P = 0.019], and LV mass [HR 1.01 (1.005-1.019), P = 0.002] were independent predictors of VT recurrence.

CONCLUSION

Pre-procedural LGE-CMR is a helpful and feasible technique to identify patients with high risk of VT recurrence after ablation. LV mass, septal LGE distribution, and transmural channels were predictive factors of post-ablation VT recurrence.

Variables affecting the quality of anticoagulation in atrial fibrillation patients newly initiating vitamin K antagonists: insights from the national and multicentre SULTAN registry

AIMS

Vitamin K antagonists (VKAs) are effective drugs reducing the risk for stroke in atrial fibrillation (AF), but the benefits derived from such therapy depend on the international normalized ratio (INR) maintenance in a narrow therapeutic range. Here, we aimed to determine independent variables driving poor anticoagulation control [defined as a time in therapeutic range (TTR) <65%] in a 'real world' national cohort of AF patients.

METHODS AND RESULTS

The SULTAN registry is a multicentre, prospective study, involving patients with non-valvular AF from 72 cardiology units expert in AF in Spain. At inclusion, all patients naïve for oral anticoagulation were started with VKAs for the first time. For the analysis, the first month of anticoagulation and those patients with <3 INR determinations were disregarded. Patients were followed up during 1 year. A total of 870 patients (53.9% male, the mean age of 73.6 ± 9.2 years, mean CHA2DS2-VASc and HAS-BLED of 3.3 ± 1.5 and 1.4 ± 0.9, respectively) were included in the full analysis set. In overall, 7889 INR determinations were available. At 1-year, the mean TTR was 63.1 ± 22.1% and 49.2% patients had a TTR < 65%. Multivariate Cox regression analysis showed that coronary artery disease [odds ratio (OR) 1.81, 95% confidence interval (CI) 1.14-2.87; P = 0.012] and amiodarone use (OR 1.54, 95% CI 1.01-2.34; P = 0.046) were independently associated with poor quality of anticoagulation (TTR <65%).

CONCLUSION

This study demonstrated that the quality of anticoagulation in AF patients newly starting VKAs is sub-optimal. Previous coronary artery disease and concomitant use of amiodarone were identified as independent variables affecting the poor quality of VKA therapy during the first year.

Cost-effectiveness of implantable cardioverter-defibrillators for primary prevention of sudden cardiac death

INTRODUCTION AND OBJECTIVES

Implantable cardioverter-defibrillators (ICD) are a cost-effective alternative for secondary prevention of sudden cardiac death, but their efficiency in primary prevention, especially among patients with nonischemic heart disease, is still uncertain.

METHODS

We performed a cost-effectiveness analysis of ICD plus conventional medical treatment (CMT) vs CMT for primary prevention of cardiac arrhythmias from the perspective of the national health service. We simulated the course of the disease by using Markov models in patients with ischemic and nonischemic heart disease. The parameters of the model were based on the results obtained from a meta-analysis of clinical trials published between 1996 and 2018 comparing ICD plus CMT vs CMT, the safety results of the DANISH trial, and analysis of real-world clinical practice in a tertiary hospital.

RESULTS

We estimated that ICD reduced the likelihood of all-cause death in patients with ischemic heart disease (HR, 0.70; 95%CI, 0.58-0.85) and in those with nonischemic heart disease (HR, 0.79; 95%CI, 0.66-0.96). The incremental cost-effectiveness ratio (ICER) estimated with probabilistic analysis was €19 171/quality adjusted life year (QALY) in patients with ischemic heart disease and €31 084/QALY in those with nonischemic dilated myocardiopathy overall and €23 230/QALY in patients younger than 68 years.

CONCLUSIONS

The efficiency of single-lead ICD systems has improved in the last decade, and these devices are cost-effective in patients with ischemic and nonischemic left ventricular dysfunction younger than 68 years, assuming willingness to pay as €25 000/QALY. For older nonischemic patients, the ICER was around €30 000/QALY.

Proximity to the descending aorta predicts regional fibrosis in the adjacent left atrial wall: aetiopathogenic and prognostic implications

AIMS

Left atrial (LA) fibrosis is present in patients with atrial fibrillation (AF) and can be visualized by magnetic resonance imaging with late gadolinium enhancement (LGE-MRI). Previous studies have shown that LA fibrosis is not randomly distributed, being more frequent in the area adjacent to the descending aorta (DAo). The objective of this study is to analyse the relationship between fibrosis in the atrial area adjacent to the DAo and the distance to it, as well as the prognostic implications of this fibrosis.

METHODS AND RESULTS

Magnetic resonance imaging with late gadolinium enhancement was obtained in 108 patients before AF ablation to analyse the extent of LA fibrosis and the distance DAo-to-LA. A high-density electroanatomic map was performed in a subgroup of 16 patients to exclude the possibility of an MRI artifact. Recurrences after ablation were analysed at 1 year of follow-up. The extent of atrial fibrosis in the area adjacent to the DAo was inversely correlated with the distance DAo-to-LA (r = -0.34, P < 0.001). This area had the greatest intensity of LGE [image intensity ratio (IIR) 1.14 ± 0.15 vs. 0.99 ± 0.16; P < 0.001] and also the lowest voltage (1.07 ± 0.86 vs. 1.54 ± 1.07 mV; P < 0.001) and conduction velocity (0.65 ± 0.06 vs. 0.96 ± 0.57 mm/ms; P < 0.001). The extent of this regional fibrosis predicted recurrence after AF ablation [hazard ratio (HR) 1.02, 95% CI 1.01-1.03; P = 0.01], however total fibrosis did not (HR = 1.01, 95% CI 0.97-1.06, P = 0.54).

CONCLUSIONS

Atrial fibrosis was predominantly located in the area adjacent to the DAo, and increased with the proximity between the two structures. Furthermore, this regional fibrosis better predicted recurrence after AF ablation than total atrial fibrosis.

Scar channels in cardiac magnetic resonance to predict appropriate therapies in primary prevention

BACKGROUND

Scar characteristics analyzed by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) are related with ventricular arrhythmias. Current guidelines are based only on the left ventricular ejection fraction to recommend an implantable cardioverter-defibrillator (ICD) in primary prevention.

OBJECTIVES

Our study aims to analyze the role of imaging to stratify arrhythmogenic risk in patients with ICD for primary prevention.

METHODS

From 2006 to 2017, we included 200 patients with LGE-CMR before ICD implantation for primary prevention. The scar, border zone, core, and conducting channels (CCs) were automatically measured by a dedicated software.

RESULTS

The mean age was 60.9 ± 10.9 years; 81.5% (163) were men; 52% (104) had ischemic cardiomyopathy. The mean left ventricular ejection fraction was 29% ± 10.1%. After a follow-up of 4.6 ± 2 years, 46 patients (22%) reached the primary end point (appropriate ICD therapy). Scar mass (36.2 ± 19 g vs 21.7 ± 10 g; P < .001), border zone mass (26.4 ± 12.5 g vs 16.0 ± 9.5 g; P < .001), core mass (9.9 ± 8.6 g vs 5.5 ± 5.7 g; P < .001), and CC mass (3.0 ± 2.6 g vs 1.6 ± 2.3 g; P < .001) were associated with appropriate therapies. Scar mass > 10 g (25.31% vs 5.26%; hazard ratio 4.74; P = .034) and the presence of CCs (34.75% vs 8.93%; hazard ratio 4.07; P = .003) were also strongly associated with the primary end point. However, patients without channels and with scar mass < 10 g had a very low rate of appropriate therapies (2.8%).

CONCLUSION

Scar characteristics analyzed by LGE-CMR are strong predictors of appropriate therapies in patients with ICD in primary prevention. The absence of channels and scar mass < 10 g can identify patients at a very low risk of ventricular arrhythmias in this population.

Ventricular tachycardia burden reduction after substrate ablation: Predictors of recurrence

BACKGROUND

Substrate-based ventricular tachycardia (VT) ablation is a first-line treatment in patients with structural cardiac disease and sustained VT refractory to medical therapy. Despite technological improvements and increased knowledge of VT substrate, recurrence still is frequent. Published data are lacking on the possible reduction in VT burden after ablation despite recurrence.

OBJECTIVE

The purpose of this study was to assess VT burden reduction during long-term follow-up after substrate ablation and identify predictors of VT recurrence.

METHODS

We analyzed 234 consecutive VT ablation procedures in 207 patients (age 63 ± 14.9 years; 92% male; ischemic heart disease in 65%) who underwent substrate ablation in a single center from 2013 to 2018.

RESULTS

After follow-up of 3.14 ± 1.8 years, the VT recurrence rate was 41.4%. Overall, a 99.6% reduction in VT burden (median VT episodes per year: preprocedural 3.546 [1.347-13.951] vs postprocedural 0.001 [0-0.689]; P = .001) and a 96.3% decrease in implantable cardioverter-defibrillator (ICD) shocks (preprocedural 1.145 [0.118-4.467] vs postprocedural 0.042 [0-0.111] per year; P = .017) were observed. In the subgroup of patients who experienced VT recurrences, VT burden decreased by 69.2% (median VT episodes per year: preprocedural 2.876 [1.105-8.801] vs postprocedural 0.882 [0.505-2.283]; P <.001). Multivariable analysis showed persistence of late potentials (67% vs 19%; hazard ratio 3.18 [2.18-6.65]; P <.001) and lower left ventricular ejection fraction (EF) (30 [25-40] vs 39 [30-50]; P = .022) as predictors of VT recurrence.

CONCLUSION

Despite a high recurrence rate during long-term follow-up, substrate-based VT ablation is related to a large reduction in VT burden and a decrease in ICD therapies. Lower EF and persistence of late potentials are predictors of recurrence.

Optimized single-point left ventricular pacing leads to improved resynchronization compared with multipoint pacing

BACKGROUND

Multipoint pacing (MPP) in cardiac resynchronization therapy (CRT) activates the left ventricle from two locations, thereby shortening the QRS duration and enabling better resynchronization; however, compared with conventional CRT, MPP reduces battery longevity. On the other hand, electrocardiogram-based optimization using the fusion-optimized intervals (FOI) method achieves more significant reverse remodeling than nominal CRT programming. Our study aimed to determine whether MPP could attain better resynchronization than single-point pacing (SPP) optimized by FOI.

METHODS

This prospective study included 32 consecutive patients who successfully received CRT devices with MPP capabilities. After implantation, the QRS duration was measured during intrinsic rhythm and with three pacing configurations: MPP, SPP-FOI, and MPP-FOI. In 14 patients, biventricular activation times (by electrocardiographic imaging, ECGI) were obtained during intrinsic rhythm and for each pacing configuration to validate the findings. Device battery longevity was estimated at the 45-day follow-up.

RESULTS

The SPP-FOI method achieved greater QRS shortening than MPP (-56 ± 16 vs. -42 ± 17 ms, p < .001). Adding MPP to the best FOI programming did not result in further shortening (MPP-FOI: -58 ± 14 ms, p = .69). Although biventricular activation times did not differ significantly among the three pacing configurations, only the two FOI configurations achieved significant shortening compared with intrinsic rhythm. The estimated battery longevity was longer with SPP than with MPP (8.1 ± 2.3 vs. 6.3 ± 2.0 years, p = .03).

CONCLUSIONS

SPP optimized by FOI resulted in better resynchronization and longer battery duration than MPP.

Extrasystoles in adults with congenital heart disease: treatment options

The prevalence of congenital heart disease (CHD) is estimated to be almost one in 100 newborns, with > 90% of patients with CHD surviving into adulthood due to medical and surgical advances in recent decades. The rationale for treatment of ventricular premature beats (VPBs) in the general population without underlying structural heart disease is mainly based on the presence of symptoms and/or the risk for developing VPB-induced cardiomyopathy in patients with very frequent VPBs. In CHD, the same general principles apply, but the clinical picture is often more complicated due to the presence of symptoms and/or systolic dysfunction resulting from the underlying heart disease itself. Sudden cardiac death due to ventricular arrhythmias is a major concern in the CHD population, although its incidence is relatively low (<0.1%/year). Beta-blockers are the first-line medical treatment for CHD patients with VPBs, although no dedicated studies are available on the use of beta-blockers or anti-arrhythmic drugs in patients with CHD for this indication. Catheter ablation has evolved in recent years as an important treatment modality for cardiac arrhythmias, generally showing superior efficacy over medical treatment for most types of arrhythmias. However, recent technological advances have led to improved methods for ablation even in complex underlying anatomical substrates, with possibilities for image fusion between three-dimensional imaging modalities and electroanatomical mapping systems during the procedure. In addition to a discussion of the above, the article also presents two examples of VPB ablation in CHD patients.

Magnetic resonance-guided re-ablation for atrial fibrillation is associated with a lower recurrence rate: a case–control study

Aims

Our aim was to analyse whether using delayed enhancement cardiac magnetic resonance imaging (DE-CMR) to localize veno-atrial gaps in atrial fibrillation (AF) redo ablation procedures improves outcomes during follow-up.

Methods and results

We conducted a case–control study with 35 consecutive patients undergoing a DE-CMR-guided Repeat-pulmonary vein isolation (Re-PVI) procedure. Those with more extensive ablations (e.g. roof lines, box) were excluded. Patients were matched for age, sex, AF pattern, and left atrial dimension with 35 patients who had undergone a conventional Re-PVI procedure guided with a three dimensional (3D)-navigation system. Procedural characteristics were recorded, and patients were followed for 24 months in a specialized outpatient clinic. The primary endpoint was freedom from recurrent AF, atrial tachycardia, or flutter. The duration of CMR-guided procedures was shorter compared to the conventional group (161 ± 52 vs. 195 ± 72 min, respectively, P = 0.049), with no significant differences in fluoroscopy or total radiofrequency time. At the 2-year follow-up, more patients in the DE-CMR-guided group remained free from recurrences compared with the conventional group (70% vs. 39%, respectively, P = 0.007). In univariate Cox-regression analyses, AF pattern [persistent AF, hazard ratio (HR) 2.66 (1.27–5.46), P = 0.006] and the use of DE-CMR [HR 0.36 (0.17–0.79), P = 0.009] predicted recurrences during follow-up; both factors remained independent predictors in multivariate analyses.

Conclusion

The substrate characterization provided by DE-CMR facilitates the identification of anatomical veno-atrial gaps and associates with shorter procedures and better clinical outcomes in repeated AF ablation procedures.

129Magnetic resonance predictors of ventricular tachycardia recurrence after radiofrequency substrate ablation: septal and transmural channels

 

Ventricular tachycardia (VT) substrate-based ablation has become a gold standard in patients with structural heart disease. Success of VT ablation is related with mortality reduction.

Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) is a powerful technique to assess substrate of VT. Myocardial fibrosis is electrically inert (Core) but it is surrounded by a ‘‘border-zone (BZ)’’ where normal cardiomyocytes intermingle with dense bundles of fibrosis. Slow impulse conduction in the BZ allows for the re-entry circuits leading to VT. Both the presence and extent of LGE have been associated with VT and SCD risk. LGE-CMR tissue characterization can be depicted as pixel signal intensity (PSI) maps and can guide VT ablation.

The aim of this study was to analyze possible VT recurrence predictors in a long term follow-up of patients that underwent VT ablation (endo and/or epicardial) related with LGE-CMR PSI maps.

We analyzed 234 consecutive patients (age: 63.2 ± 14 years, follow-up: 3.14 years ±1.8) undergoing VT ablation with scar-dechannelling technique at a single center from 2013 to 2018.  110 patients underwent a preprocedural LGE-CMR, and in 94 patients (85,5%) a CMR-aided ablation using the PSI maps was performed.

All LGE-CMR images were semi-automatically processed using a dedicated software. PSI-based algorithm was applied to characterize the hyperenhanced area as core or BZ, using fixed threshold of the maximum intensity. A LV 3D shell was obtained and were imported into the navigation system. In the PSI maps, heterogenous tissue channels were defined as a continuous corridor of BZ surrounded by scar core or an anatomic barrier that connects 2 areas of healthy tissue.

Results

Overall recurrence of VT was 41.8 %. There was ICD shock reduction, from 43,6% to a 28,2% (ICD shocks before ablation 2,23 ± 7,32, after: 1,10 ± 2,92).

Left ventricle mass predicted significantly VT recurrence (Mean 168,3 ± 53,3 vs 152,3 ± 46,4 g, HR 1,02 [1,01-1,02], p &lt; 0.001). LGE distribuition was predictive of VT recurrence when a more than 40% of the interventricular septum was involved (62,5% vs 37,8%; HR 1,6 [1,01-1,02]; p = 0,044). No differences in recurrence were found among the patterns of LGE distribution (transmural/epicardial/subendocardial or peculiar segments localizations). The amount of BZ and the total amont of Core + BZ was related with VT recurrence (BZ 26,6 ± 13,9 vs 19,56 ± 9,69 g, HR 1,03 [1,01-1,06], p = 0,012; total Core + BZ 37,1 ± 18,2 vs 29,0 ± 16,3 g, HR 1,02 [1,00-1,04], p = 0,033). Finally VT recurrence was higher in patients with channels with transmural path (66,7% vs 31,4%, HR 3,25 [1,70-6,23], p &lt; 0,001) or midmural channels (54,3% vs 27,6%, HR 2,49 [1,21–5,13], p = 0,013).

CMR-aided scar dechanneling is a helpful and feasible technique which could identify patients with high risk of VT recurrence. High left ventricular mass, septal LGE distribution, transmural and midmural heterogeneous tissue channels were predictive factors of post ablation VT recurrence.

Abstract Figure. VTchannel & heterogeoneus tissue channel

P1163Correction of septal flash excursion with his bundle pacing

Funding Acknowledgements

Grant from the Catalan Society of Cardiology

Background

His bundle pacing (HBP) directly stimulates the conduction system and could therefore correct asynchrony and evolve as a more physiological pacing approach. Septal flash (SF) is a fast contraction and relaxation of the septum occurring during the isovolumetric contraction period. It is a specific marker of cardiac dyssynchrony.  

Purpose

Evaluate whether HBP corrects SF in patients with an indication for CRT or RV pacing.

Methods

A cohort of 20 consecutive patients undergoing HBP at our center was analyzed. HBP indications were:  Group A (n = 3): left bundle branch block (LBBB) and left ventricular (LV) dysfunction (LV ejection fraction [LVEF] &lt; 35%); Group B (n = 14): LV dysfunction (LVEF &lt; 50%) and atrio-ventricular block requiring permanent pacing; Group C (ablate&pace, n = 3): atrio-ventricular node ablation due to rapid atrial fibrillation.

Patients in groups B and C had a RV backup lead implanted, in line with current recommendations. The presence of SF was analyzed in 2D-echocardiography at 15 days post-implant. SF excursion was quantified using M-mode in parasternal short and long axis views as the highest amplitude of the early inward motion. Baseline SF excursion was determined during intrinsic rhythm (group A) or RV pacing (groups B and C). For each patient, the pair of measurements (baseline, HBP) in the axis with the highest baseline SF was selected.

Results

Mean LVEFs were 21 ± 8%, 32 ± 6%, and 41 ± 18% for groups A, B and C, respectively. HBP shortened QRS duration by 42 ± 15 ms and 45 ± 23 ms in groups A (Baseline QRS - HBP QRS) and B + C (RV pacing QRS - HBP QRS), respectively. At baseline, all patients except 1 had SF (Fig. 1A). The mean SF excursion was 4.3 ± 1.9 mm, with SF excursion being larger in group A than in the RV-paced groups (6.3 ± 1.5 mm vs. 3.9 ± 1.8 mm for groups A and B + C, respectively, p = 0.04). HBP abolished SF in 3 patients (15%) and, on average, decreased SF excursion by 2.3 mm (95% CI 1.3-3.2), irrespective of pacing indication (Fig. 1B). The degree of SF excursion reduction after HBP significantly correlated with QRS shortening (r = 0.53, p = 0.024) (Fig 1C).

Conclusions

In conclusion, we show that HBP results in acute correction or decrease of SF, thereby improving LBBB- or RV-induced mechanical dyssynchrony.

Abstract Figure. Septal Flash and His pacing

45Improving the optimization of cardiac resynchronization therapy: Does multipoint left ventricular pacing shorten the paced-QRS duration compared to the fusion-optimized intervals method?

Funding Acknowledgements

Cardiac Pacing Scholarship from the Spanish Society of Cardiology (SEC)

Background

Electrocardiogram-based optimization of cardiac resynchronization therapy (CRT) using the fusion-optimized intervals (FOI) method has demonstrated to improve both acute hemodynamic response and left ventricle (LV) reverse remodeling compared to nominal programming of CRT. FOI optimizes the atrioventricular (AV) and ventriculo-ventricular (VV) intervals to achieve the shortest paced-QRS duration. The recent development of multipoint pacing (MPP) enables the activation of the LV from 2 locations, also shortening the QRS duration compared to conventional biventricular pacing.

Purpose

To determine if MPP reduces the paced-QRS duration compared to FOI optimization. 

Methods

This prospective clinical study included 25 consecutive patients who successfully received a CRT with MPP pacing capability. All patients were in sinus rhythm and had an PR interval below 250 ms. The QRS duration was measured with a 12-lead digital electrocardiography (screen speed of 200 mm/s) at baseline and using 3 different configurations: MPP, FOI and a combined FOI-MPP strategy. In MPP, the intervals were (based on previous studies): 1) AV 130 ms, 2) Right ventricular (RV)-LV2 (Δ1) 5 ms, and 3) LV1-LV2 (Δ2) 5 ms. In FOI, AV and VV intervals were optimized to achieve fusion between intrinsic conduction and biventricular pacing. In FOI-MPP, the Δ2 was set at 5 ms, while AV and Δ1 intervals were optimized using the FOI method. The CRT device was programmed with the configuration that achieved a greater paced-QRS shortening. After 45 days, battery life was estimated.

Results

  Mean age was 65 ± 10 years, 20 were men (80%) and baseline QRS duration was 177 ± 17 ms. The FOI method bested nominal MPP (QRS shortened by 58 ± 16 ms vs 43 ± 16 ms, respectively, p = 0.002). Adding MPP to the narrowest QRS by FOI did not result in further shortening (FOI: 58 ± 16 ms vs FOI-MPP: 59 ± 13 ms, p = 0.81). The final configuration was FOI method alone in most cases (n = 16, 64%) and FOI-MPP in all others (n = 9, 36%; figure). In total, 10 out of 25 patients (40%) were not candidates to MPP due to: 1) pacing thresholds exceeding 3.5 V/0.4 ms at the distal or proximal electrode (8, 32%), and 2) phrenic stimulation (2, 8%). Estimated battery longevity was longer in patients receiving FOI as compared to MPP (8.3 ± 2.1 years vs. 6.2 ± 2.2 years, p = 0.04).

Conclusion

In CRT, the FOI method is not improved by coupling with MPP.  Up to 40% of patients are not candidates for MPP due to high thresholds or phrenic stimulation. The use of MPP in unselected patients would result in a decrease of battery longevity, without any additional benefit over FOI.

Abstract Figure.